V/A+ 는다고/ㄴ다고/다고 하니까 V+ 을게요/ㄹ게요.

It is used when the speaker expresses or promises his will to do something, citing what he has heard from others as a reason.

For ‘-는다고/ㄴ다고/다고 하니까’, if the stem of an action verb ends with a vowel or ‘ㄹ’, you use ‘ㄴ다고 하니까’, with another consonant you use ‘-는다고 하니까’. After the stem of a descriptive verb, you use ‘-다고 하니까’.

For ‘-을게요/ㄹ게요’, if the stem of an action verb ends with a vowel or ‘ㄹ’, you use -ㄹ게요’, with another consonant, you should use ‘- 을게요’.

유양 씨가 다리가 아파서 못 한다고 하니까 제가 대신 할게요.
Yooyang said she couldn’t do it because her legs hurt, so I’ll do it for her.

회의가 조금 있으면 끝난다고 하니까 끝나자마자 빨리 갈게요.
They said the meeting will be over soon, so I’ll be there as soon as I’m done.

준수 씨는 요즘 바쁘다고 하니까 전화 대신 이메일을 보낼게요.
Junsu said he’s busy these days, so I’ll send you an e-mail instead of calling.

Conversation:

이번 주말에 같이 스키장에 갈래?
Would you like to go skiing with me this weekend?

난 좋아. 근데 스키장 입장료가 비싸지는 않아?
I like it. But isn’t the entrance fee for a ski resort expensive?

그래도 할인되는 신용카드가 꽤 많아. 학생증도 있으면 할인이 돼.
Still, there are quite a lot of credit cards that you can get discounts. You also can get a discount if you have a student ID.

학생은 얼마나 할인돼?
How much is the discount for students?

학생은 10퍼센트 할인되고 신용카드 중에는 50퍼센트 할인되는 제휴 카드도 있어.
There is a 10 percent discount for students and among credit cards, there are partnership cards of 50 percent discount.

신용카드가 정말 할인율이 높구나. 난 그런 카드가 하나도 없는데.
The discount rate for a credit card is really high. But I don’t have any of those cards.

내 카드는 동반 2인까지 40퍼센트 할인해 준다고 하니까 내 카드로 결제할게.
It is said that I can get a 40 percent discount for up to two people with my card, so I will pay with mine.

고마워, 그럼 그날 밥은 내가 살게.
Thank you, then I’ll buy the meal that day.

Related words
스키장 ski resort
입장료 entrance fee
할인율 discount rate
제휴 partnership

Source: Yonsei University. Korean Language Institute